Satellites Show Climate Change Thinning Rivers, Erasing Glaciers


Drought, floods and the melting of glaciers affected almost every part of the world in 2021, according to a new WMO report.

Climate change is distorting rain patterns across the planet, leading to drought and floods, while rising temperatures are causing glaciers to melt, according to the first ever comprehensive review of water resources by the World Meteorological Organization. The WMO says it aims to publish global water reports annually from now on in response to calls for more accurate data in an era of growing demand and limited supplies.

The State of Global Water Resources report for 2021, released on Tuesday, analyzes the effects that higher temperatures are having on the planet’s freshwater bodies. Global temperatures are now 1.1C higher than in pre-industrial times, and last year was one of the seven hottest years on record.

“The impacts of climate change are often felt through water — more intense and frequent droughts, more extreme flooding, more erratic seasonal rainfall and accelerated melting of glaciers,” said WMO Secretary-General Petteri Taalas in a statement. All these events have “cascading effects on economies, ecosystems and all aspects of our daily lives.”

About three-quarters of all natural disasters between 2001 and 2018 were water related, according to UN-Water, which coordinates the United Nations’ work on water and sanitation. At the same time, 3.6 billion people, almost half of the global population, face inadequate access to water for at least a month every year — and that number is expected to increase to over 5 billion by mid-century.

Inconsistent measurements and a lack of data collected on the ground made it hard to understand some of the effects that climate change is having on water systems, the WMO said. Researchers filled these gaps partly with modeled data and with information from satellites in NASA’s Gravity Recovery and Climate Experiment program, or GRACE, highlighting the importance of satellites and remote sensing to measure global warming.

Here’s how some of 2021’s most relevant water impacts looked from space:

Dying glaciers

Glacial melting accelerated globally in 2021. Masses of ice in Western Canada and the US and in Central Europe experienced the most significant losses over the past four decades, the WMO report shows. Running water from melting glaciers increases at first, feeding rivers and lakes nearby until it reaches a turning point that scientists call “peak water.” After that, the runoff declines and the areas depending on that water can experience drought.

Widening lakes

Also known among glaciologists as the “Third Pole,” the Tibetan Plateau holds the largest reserve of freshwater outside the polar regions. The water is mostly stored in glaciers high up in the mountains. Higher temperatures are speeding their melting, shrinking the glaciers and occasionally leading to flash floods. Large amounts of water end up in mountain lakes, which are growing as a result.

Dwindling rivers

Drought in several parts of the US worsened in 2021, with the entire west of the country affected from the month of June. Discharge data from the Colorado, Missouri and Mississippi Rivers shows the amount of water they were carrying was far below normal.

In some places, the amount of water stored in land is growing — nowhere more so than in the Lake Victoria region in Africa. But overall, rivers are shrinking more than they are growing, a trend that continued in 2021.

Extreme drought

The water deficit that Iran, Iraq and Syria experienced in 2020 was intensified by a warm winter that continued in 2021. That meant lakes and reservoirs didn’t replenish ahead of the hot summer months. The resulting drought affected up to 12 million people in Iraq and Syria and 4.8 million in Iran, leading to deadly clashes in the Khuzestan province.

Drought in the Horn of Africa has led to a devastating food crisis affecting 18 million. Not even intense rainfall between December 2020 to February 2021 — typically the dry season in the region — helped alleviate the situation.

Deadly floods

Changing weather patterns have led to unprecedented amounts of water falling in very short periods, giving rise to devastating floods. In 2021 floods in Western Europe killed 219 people, causing up to 46 billion euros in damage.

Turkey, Afghanistan, India and China’s Henan province were also hit by floods that led to over 1,500 fatalities. It was a stark reminder that the effects of climate change are being felt everywhere.


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